Dc-88a derivatives useful as antitumor agents

ABSTRACT

A DC-88A derivative represented by general formula: ##STR1## wherein ##STR2## represents ##STR3## has an excellent antitumor activity and is useful as an anti-tumor agent.

This application is a division of application Ser. No. 07/392,271 filed Aug. 10, 1989, now U.S. Pat. No. 5,084,468.

BACKGROUND OF THE INVENTION

The present invention relates to novel DC-88A derivatives. The compounds have an excellent antitumor activity and are useful as antitumor agents.

WO 87/06265 (EP-A-0271581) discloses DC-88A produced by microorganisms belonging to the genus Streptomyces exhibits not only an antibacterial activity against various bacteria but also an antitumor against lymphocytic leukemia P388, etc.

DC-88A has the following structure. ##STR4##

DC-89A1 which is a compound having a structure similar to DC-88A is disclosed in WO 87/06265; DC-89A2, DC-89B1 and DC-89B2 are disclosed in Japanese Patent Application No. 182866/88. DC-89A1, DC-89A2, DC-89B1 and DC-89B2 have the following structures. ##STR5##

These compounds show an antibacterial activity against various bacteria and an antitumor activity against lymphocytic leukemia P388, etc.

CC-1065 and its derivatives which are structurally similar to DC-88A and exhibit an antitumor activity are also disclosed in Japanese Published Unexamined Patent Application Nos. 64695/79 and 193989/85.

DC-88A derivatives having an excellent antitumor activity have always been demanded.

SUMMARY OF THE INVENTION

The present invention provides novel DC-88A derivatives represented by general formula (A): ##STR6## wherein X represents chlorine, bromine or iodine; R represents one member selected from hydrogen, and the groups (a), (b), (c), (d) and (e): ##STR7## wherein each of X₁, X₂ and X₃ independently represents hydrogen, --OH, --CHO, --OR₁ (wherein R₁ represents a straight or branched alkyl having 1 to 7 carbon atoms or benzyl), --OCOR₁ (wherein R₁ has the same significance as described above), --NO₂, --NH₂, --NR₂ R₃ (wherein each of R₂ and R₃ represents hydrogen or R₁, and R₁ has the same significance as described above), --NR₂ COR₁ (wherein R₁ and R₂ have the same significances as described above), --NHCO₂ R₁ (R₁ has the same significance as described above), --NHCONH₂, --SH, --SR₁ (wherein R₁ has the same significance as described above), --SCOR₁ (wherein R₁ has the same significance as described above), chlorine or bromine; or X₁ and X₂ are combined together to represent --OCH₂ O--; Z represents O, S or NH; Y represents --CH₂ --_(l) (wherein l is an integer of 0 to 7), --CH═CH_(m) (wherein m is an integer of 1 or 2), --Y'-- (wherein Y' represents O, S or NH), --Y'-- (CH₂)_(n) --(wherein Y' has the same significance as described above and n represents an integer of 1 to 4), --(CH₂)_(n) --Y'-- (wherein Y' and n have the same significance as described above) or ##STR8## (wherein Y' and Z have the same significances as described above and p represents an integer of 0 to 4); ##STR9## wherein X₁, X₂, X₃ and Z have the same significances as described above; X₄ represents O, S, NH or NR₁ (wherein R₁ has the same significance as described above); and X₅ represents --Nα, --CH═or --CH₂ --; provided that when X is Cl or Br and X₁, X₂ and X₃ are 5--OCH₃, 6--OCH₃ and 7--OCH₃, respectively and Z is O and X₄ is --NH--, X₅ is ═N-- or --CH₂ --; ##STR10## wherein R₄ represents a straight or branched alkyl having 1 to 7 carbon atoms or an alkyl wherein any one of the hydrogen atoms in the above alkyl is substituted with X₁ ; and X₁ has the same significance as described above;

    --R.sub.5 --R.sub.6

wherein R₅ represents a substituent obtained by removing hydrogen from --NH₂ which is represented by X₁, X₂ or X₃ of the substituent group (a), (b) or (c); and R₆ represents the substituent group (a), (b) or (c) described above; or,

(e) a residue obtained by removing hydroxy of the carboxylic acid in an α-amino acid, benzyloxycarbonyl group or tert-butoxycarbonyl group, and pharmaceutically acceptable salts thereof.

DETAILED DESCRIPTION OF THE INVENTION

The compounds represented by general formula (A) are hereinafter referred to as Compound (A).

Compounds represented by formulae with numbers I, II, III . . . are similarly referred to as Compound I, II, III . . .

Compound (II)-a and Compound (III)-a are included in Compound (II) and Compound (III), respectively.

In the definition of the groups (a) and (c) under the substituent R, a straight or branched alkyl having 1 to 7 carbon atoms includes, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, etc.

In the definition of the group (e) under the substituent R, the α-amino acid includes, for example, glycine, alanine, leucine, glutamic acid, aspartic acid, lysine, serine, proline, phenylalanine, tyrosine, tryptophan and histidine.

Processes for producing Compound (A) are described below.

In general formula (A), Compound (IV) wherein ##STR11## and R is hydrogen can be obtained by reacting DC-88A with a base. ##STR12##

As the base, mention may be made of sodium methoxide, sodium hydroxide, potassium hydroxide, potassium t-butoxide, triethylamine, 1,8-diazabicycloundecene (DBU), potassium carbonate, etc. The base is used generally in 1 to 3 molar equivalents based on DC-88A. As an inert solvent, water, methanol, tetrahydrofuran (THF), dioxane, acetonitrile, etc. are used singly or as admixture. The reaction is carried out generally at -20to 50° C. and completed in 30 minutes to 5 hours. Purification is effected by column chromatography or high performance liquid chromatography (HPLC).

In general formula (A), Compound (I) wherein: ##STR13## and R is the substituents other than hdyrogen can be produced by the following step. ##STR14## Compound (I) can be produced by reacting compound (IV) either with a carboxylic acid reactive derivative, or with isocyanate, isothiocyanate or benzyl chloroformate derivative in an inert solvent in the presence of a base.

Examples of the base include sodium hydride, lithium diisopropylamide, potassium t-butoxide, triethylamine, 4-dimethylaminopyridine, etc. The base is used in 1 to 2 molar equivalents based on Compound (IV). As the inert solvent, dimethylformamide, THF, toluene, dimethylsulfoxide, pyridine, etc. may be used singly or as admixture. Examples of the carboxylic acid reactive derivative include an acid chloride, an acid anhydride (an acid anhydride produced using N,N'-dicyclohexylcarbodiimide, etc.), an activated ester (p-nitrophenyl ester, N-hydroxysuccinimide ester, etc.), an activated amide (imidazolide, etc.), a mixed acid anhydride (mixed acid anhydride with monoethyl carbonate, monoisobutyl carbonate, etc.), etc. The reactive derivative is used generally in 1 to 2 molar equivalents based on Compound (IV). Isocyanate or isothiocyanate is used in 1 to 2 molar equivalents based on Compound (IV). The reaction is carried out generally at -50° to 30° C. and completed in 30 minutes to one day.

Among the carboxylic acid reactive derivative, isocyanate and isothiocyanate, those containing reactive functional groups therein should be protected upon acylation. The thus obtained protected compounds are acylated and the protective group is removed after the acylation. Selection and removal of protective groups are described in T. W. Greene, "Protective Groups in Organic Synthesis", John Wiley & Sons, 1980, in detail.

Processes for producing Compound (II) of general formula (A) wherein: ##STR15## and Compound (III) wherein: ##STR16## are described below.

Compound (II) and Compound (III) can be obtained by reacting Compound (I) with hydrochloric acid, hydrobromic acid or hydroiodic acid in an inert solvent. ##STR17## wherein X is Cl, Br or I.

As the inert solvent, dimethylformamide, acetonitrile, methylene chloride, toluene, water, etc. may be used singly or as admixture. Hydrochloric acid (X=Cl), hydrobromic acid (X=Br) or hydroiodic acid (X=I) is used in 1 to 20 molar equivalents based on Compound (I). The reaction is carried out generally at -30° to30° C. and completed in one minute to 5 hours.

Alternatively, Compound (II) and Compound (III) can also be obtained by reacting Compound (I) with a halide of alkali metal or alkaline earth metal in a mixture of an inert solvent and a buffer solution having a pH range of 4to 6. As the inert solvent, dimethylformamide, acetonitrile, THF, dioxane, etc. may be used singly or as admixture. As the buffer solution having a pH range of 4 to 6, buffer solutions composed of potassium primary citrate-sodium hydroxide, sodium secondary citrate-sodium hydroxide, potassium primary phosphate-sodium secondary phosphate, etc. are used in a concentration of 0.05 to 0.5M. The halide of alkali metal or alkaline earth metal includes, for example, LiCl, NaCl, KCl, MgCl₂, CaCl₂, LiBr, NaBr, KBr, MgBr₂, CaBr₂, LiI, NaI, KI, MgI₂, etc. and is used generally in 2 to 30 molar equivalents based on Compound (I). The reaction is carried out generally at 0° to 50° C. and completed in 2 to 2 days.

Compound (II) and Compound (III) can also be obtained by the following process. That is, in Compound (II)-a and Compound (III)-a containing benzyloxycarbonyl group or t-butoxycarbonyl group in R which can be readily splittable, R is removed to produce Compound (V) and Compound (VI), respectively. ##STR18##

In the case of Compound (III)-a wherein R is benzyloxycarbonyl group, it is appropriate to remove R by hydrogenolysis in a conventional manner; removal with HBr--CH₃ COOH is also applicable. In the case of Compound (III)-a wherein R is t-butoxycarbonyl group, R is removed with trifluoroacetic acid. Substituent R is introduced into Compound (V) and Compound (VI) by reacting Compound (V) and Compound (VI) with one of a carboxylic acid reactive derivative, isocyanate, isothiocyanate, etc. in an inert solvent, if necessary, in the presence of a base.

As the inert solvent, dimethylformamide, THF, toluene, methylene chloride, chloroform, pyridine, etc. may be used singly or as admixture. Examples of the carboxylic acid reactive derivative include an acid chloride, an acid anhydride, an activated ester (p-nitrophenyl ester, N-hydroxysuccinimide ester, etc.), an activated amide (imidazolide, etc.), a mixed acid anhydride (mixed acid anhydride with monoethyl carbonate, monoisobutyl carbonate, etc.). The reactive derivative, isocyanate or isothiocyanate is used generally in 1 to 2 molar equivalents based on Compound (V) or Compound (VI). The reaction is carried out generally at -20° to 50° C. and completed in 30 minutes to one day. Alternatively, the carboxylic acid and a condensing agent are simultaneously reacted with Compound (V) or Compound (VI) in an inert solvent to produce Compound (II) or Compound (III). As the condensing agent, dicyclohexylcarbodiimide or similar carbodiimides are appropriate. The condensing agent and the carboxylic acid are both employed in 1 to 2 molar equivalents based on Compound (V) or Compound (VI). As the inert solvent, acetonitrile, methylene chloride, THF, dimethylformamide, etc. may be used. The reaction is carried out generally at -20° to 50° C. and completed in 30 minutes to one day.

After completion of the reaction in each step, a buffer solution is added to the reaction mixture, if necessary, followed by extracting with a non-aqueous solvent such as ethyl acetate, chloroform, ether, etc. After washing with water, a sodium chloride aqueous solution, etc., the extract is dried over anhydrous sodium sulfate and the solvent is distilled off. The residue obtained is subjected to silica gel column chromatography, thin layer chromatography, high performance liquid chromatography, recrystallization, etc. to effect purification.

The structure and compound number of representative compounds which fall under Compound (I), Compound (II) and Compound (III) are shown in Table 1. In Table 1, types (I), (II) and (III) indicate that they fall under Compound (I), Compound (II) and Compound (III), respectively.

                                      TABLE 1                                      __________________________________________________________________________      ##STR19##                                                                      ##STR20##                                                                     Compound No.                                                                           Type                                                                              R                                X                                  __________________________________________________________________________     1       (I)                                                                                ##STR21##                       --                                 2       (II)                                                                               ##STR22##                       Br                                 3       (II)                                                                               ##STR23##                       Br                                 4       (II)                                                                               ##STR24##                       Br                                 5       (II)                                                                               ##STR25##                       I                                  6       (I)                                                                                ##STR26##                       --                                 7       (II)                                                                               ##STR27##                       Br                                 8       (I)                                                                                ##STR28##                       --                                 9       (II)                                                                               ##STR29##                       Br                                 10      (I)                                                                                ##STR30##                       --                                 11      (II)                                                                               ##STR31##                       Br                                 12      (I)                                                                                ##STR32##                       --                                 13      (II)                                                                               ##STR33##                       Br                                 14      (I)                                                                                ##STR34##                       --                                 15      (II)                                                                               ##STR35##                       Br                                 16      (I)                                                                                ##STR36##                       --                                 17      (I)                                                                                ##STR37##                       --                                 18      (I)                                                                               H                                --                                 19      (II)                                                                               ##STR38##                       Br                                 20      (II)                                                                               ##STR39##                       Br                                 21      (I)                                                                                ##STR40##                       --                                 22      (II)                                                                               ##STR41##                       Br                                 23      (I)                                                                                ##STR42##                       --                                 24      (II)                                                                               ##STR43##                       Br                                 25      (I)                                                                                ##STR44##                       --                                 26      (II)                                                                               ##STR45##                       Br                                 27      (I)                                                                                ##STR46##                       --                                 28      (II)                                                                               ##STR47##                       Br                                 29      (I)                                                                                ##STR48##                       --                                 30      (II)                                                                               ##STR49##                       Br                                 31      (II)                                                                               ##STR50##                       Br                                 32      (I)                                                                                ##STR51##                       --                                 33      (II)                                                                               ##STR52##                       Br                                 34      (II)                                                                               ##STR53##                       Br                                 35      (II)                                                                               ##STR54##                       Br                                 36      (II)                                                                               ##STR55##                       Br                                 37      (II)                                                                               ##STR56##                       Br                                 38      (II)                                                                               ##STR57##                       Br                                 39      (II)                                                                               ##STR58##                       Br                                 40      (II)                                                                               ##STR59##                       Br                                 41      (II)                                                                               ##STR60##                       Br                                 42      (II)                                                                               ##STR61##                       Br                                 43      (II)                                                                               ##STR62##                       Br                                 44      (II)                                                                               ##STR63##                       Br                                 45      (II)                                                                               ##STR64##                       Br                                 46      (II)                                                                               ##STR65##                       Br                                 47      (II)                                                                               ##STR66##                       Br                                 48      (II)                                                                               ##STR67##                       Br                                 49      (II)                                                                               ##STR68##                       Br                                 50      (II)                                                                               ##STR69##                       Br                                 51      (I)                                                                                ##STR70##                       --                                 52      (I)                                                                                ##STR71##                       --                                 53      (I)                                                                                ##STR72##                       --                                 54      (I)                                                                                ##STR73##                       --                                 55      (II)                                                                               ##STR74##                       Br                                 56      (I)                                                                                ##STR75##                       --                                 57      (I)                                                                                ##STR76##                       --                                 58      (I)                                                                                ##STR77##                       --                                 59      (I)                                                                                ##STR78##                       --                                 60      (I)                                                                                ##STR79##                       --                                 61      (I)                                                                                ##STR80##                       --                                 __________________________________________________________________________

Test on Growth Inhibition of HeLa S₃ cells

HeLa S₃ cells diluted to 3×10⁴ cells/ml with MEM medium containing 10% calf fetal serum and 2 mM glutamine were separately distributed by 0.1 ml each in each well of a 96 well microtiter plate.

After culturing at 37° C. overnight in a CO₂ -incubator, 0.05 ml each of a test sample appropriately diluted with MEM medium was added to each well.

After culturing the cells for 72 hours in the CO₂ -incubator, the culture supernatant was removed. After washing once with phosphate buffered physiological saline (PBS), 0.1 ml each of MEM medium containing 0.02% neutral red was added to each well and then cultured at 37° C. for an hour in the CO₂ -incubator to stain the cells. After removing the culture supernatant, the cells were washed once with physiological saline, and the dye was extracted with 0.001N HCl/30% ethanol. Absorbance at 550 mm of the extract was measured with a microplate reader. By comparing absorbance of extract of intact cells with that of the cells treated with a test compound in known concentrations, IC₅₀, i.e. a drug concentration which inhibited growth of the cells by 50% was determined.

IC₅₀ values of representative Compound (I), Compound (II) and Compound (III) are shown in Table 2.

                  TABLE 2                                                          ______________________________________                                         Compound No.   IC.sub.50 (nM)                                                  ______________________________________                                          1             1.1                                                              2             0.054                                                            3             0.0034                                                           4             0.10                                                             5             0.011                                                            6             2.3                                                              7             5.7                                                              8             3.2                                                              9             2.6                                                             14             6.7                                                             15             3.1                                                             18             3900                                                            23             <0.024                                                          24             0.024                                                           25             7.6                                                             27             0.60                                                            28             2.5                                                             29             <0.024                                                          30             0.034                                                           31             81                                                              32             0.0075                                                          33             0.88                                                            34             0.050                                                           35             0.94                                                            37             0.74                                                            38             0.035                                                           40             0.085                                                           45             1.1                                                             46             0.4                                                             48             1.2                                                             55             0.52                                                            ______________________________________                                    

Acute Toxity Test

Using dd strain male mice weighing 20±1 g, a test compound was intraperitoneally administered. MLD (the minimum lethal dose) was determined by observing the mortality for 14 days after administration.

The results are shown in Table 3.

                  TABLE 3                                                          ______________________________________                                                        Acute Toxicity                                                  Compound No.   (MLD) mg/kg                                                     ______________________________________                                          2             0.25                                                             3             0.063                                                            4             0.25                                                             7             1.0                                                             15             4.0                                                             19             2.5                                                             22             13                                                              24             0.25                                                            26             2.2                                                             28             0.16                                                            30             0.082                                                           31             20                                                              32             0.25                                                            34             0.063                                                           35             0.25                                                            36             1.3                                                             38             0.063                                                           39             1.3                                                             40             0.31                                                            41             1.3                                                             42             2.5                                                             45             0.63                                                            46             0.63                                                            55             0.25                                                            ______________________________________                                    

Compound (A) may be used as antitumor agents singly or together with pharmacologically acceptable carriers. For example, Compound (A) is dissolved in a physiological saline solution or in an aqueous solution of glucose, lactose, mannitol, etc. to prepare a suitable pharmaceutical composition for injection. Alternatively, Compound (A) or salt thereof is freeze-dried or mixed with sodium chloride to prepare a powdery injection. The pharmaceutical composition may contain additives well known in the art of medical preparation, for example, pharmacologically acceptable salts, etc., if necessary. Although the amount of the compound for dosage varies depending upon age, condition, etc. of the patient, it is suitable to administer the compound in an amount of 0.0001 to 5 mg/kg/day for mammals including human beings. Administration is made once a day (single administration or consecutive administration) or intermittently 1 to 3 times a week or once 2 to 3 weeks, intravenously. If it is wished, oral administration is also possible in a similar dose and in a similar manner. Form of oral administration includes a tablet, a capsule, powders, granules, an ampoule, etc. These preparations contain pharmaceutical aids well known in the art of medical preparation. If it is wished, intraarterial administration, intraperitoneal administration, intrathoracic administration, etc. may also be possible in a similar dose and in a similar route.

The antitumor composition of this invention is expected to be effective for leukemia, gastric cancer, colon cancer, lung cancer, breast cancer, uterine cancer, etc. in mammals including human beings.

Certain specific embodiments of the present invention are illustrated by the following examples and reference examples.

Physicochemical properties of the compounds shown in the following examples and reference examples were determined with the following equipments.

    ______________________________________                                         NMR       JEOL, Ltd.    FX-100 (100 MHz)                                                 JEOL, Ltd.    PS-100 (100 MHz)                                                 Bruker        AM-400 (400 MHz)                                       MS        Hitachi Ltd.  M-80B                                                            Shimadzu      QP-1000                                                IR        Nippon Bunko  IR-810                                                 ______________________________________                                    

As silica gel, Wakogel C-200® manufactured by WAKO Pure Chemical Industry Co., Ltd. was used.

In the following examples and reference examples, "treated in a conventional manner" refers to the following working-up reaction.

Citrate or phosphate buffer of pH 5 is added to the reaction mixture and the mixture is extracted with ethyl acetate or chloroform. The extract is washed with saturated aqueous sodium chloride solution. After drying over anhydrous sodium sulfate, the solvent is distilled off.

EXAMPLE 1 Synthesis of Compound 18

DC-88A, 93 mg (0.18 mmol), was dissolved in 10 ml of methanol and 70 μl of methanolic solution containing 28% sodium methoxide was dropwise added to the solution under ice cooling. The mixture was stirred for 40 minutes under ice cooling, 0.1M phosphate buffer (pH 5.3) was added to the mixture, and methanol was distilled off. After adding sodium chloride to the residue, the mixture was extracted 3 times with ethyl acetate-THF. After drying over anhydrous sodium sulfate, the extract was concentrated under reduced pressure. The residue was purified by silica gel column chromatography [12 ml of silica gel, eluting solvent; chloroform: acetone=1:0-3:1] to give 49 mg of Compound 18 (yield; 97%).

Physicochemical properties of Compound 18 are as follows.

¹ H--NMR(CDCl₃) δ (ppm); 6.16 (br s 1H), 5.74 (s 1H), O=5.46 (br s 1H), 3.81 (ddd 1H J=11.0, 5.6, 1.5Hz), 3.73 (s 3H), 3.69 (d 1H J=11.0Hz), 3.03 (m 1H), 2.05 (dd 1H J=7.8, 3.5Hz), 1.63 (s 3H), 1.01 (dd 1H J=4.6, 3.5Hz)

IR (CHCl₃) ν_(max) (cm⁻¹):3450, 1740, 1685, 1560 SI--MS m/z:275 (M+1)⁺

EXAMPLE 2 Synthesis of Compound 1

In an argon atmosphere, 11.0 mg (0.26 mmol) of 60% sodium hydride was suspended in 1.0 ml of dimethylformamide and 0.7 ml of a dimethylformamide solution containing 60 mg (0.22 mmol) of Compound 18 was dropwise added to the solution at -15° to -10° C. Then the mixture was stirred at -15° to -3° C. for 20 minutes. After cooling to -30° C., 0.7 ml of a dimethyl formamide solution containing 50 mg (0.26 mmol) of indole-2-carbonyl chloride was dropwise added to the reaction mixture. The mixture was stirred at -30 to -5° C. for 50 minutes. The reaction mixture was treated in the conventional manner to give 113 mg of crude product. The crude product was purified by silica gel column chromatography (15 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 68.9 mg of Compound 1 (yield; 75.5%).

Physicochemical properties of Compound 1 are as follows.

¹ H--NMR(DMSO-d₆) δ(ppm); 11.83 (s 1H), 8.71 (s 1H), 7.68 (d 1H J=8.1Hz), 7.48 (dd 1H J=8.3, 0.8Hz), 7.28 (ddd 1H J=8.2, 7.0, 1.2Hz), 7.21 (d 1H J=1.3Hz), 7.09 (ddd 1H J=8.0, 7.0, 1.0Hz), 6.94 (s 1H), 4.59 (dd 1H J=10.5, 5.3Hz), 4.45 (d 1H J=10.5Hz), 3.61 (s 3H), 3.02 (m 1H), 1.95 (dd 1H J=7.5, 3.5Hz), 1.46 (s 3H), 1.45 (m 1H)

SI--MS m/z; 418(M+1)⁺, 419(M+2)⁺, 420(M+3)⁺, 276, 275, 217, 215

IR(KBr) ν_(max) (cm⁻¹); 3350(br), 1732, 1651, 1621

EXAMPLE 3 Synthesis of Compound 2

Compound 1, 45 mg, was dissolved in 8 ml of methylene chloride and 40 μl of 48% hydrogen bromide aqueous solution was added to the solution. The mixture was stirred at room temperature for 25 minutes. The reaction mixture was treated in a conventional manner to give 65 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 47.6 mg of Compound 2 (yield; 88.6%).

Physicochemical properties of Compound 2 are as follows.

¹ H--NMR(CDCl₃ -CD30D) δ (ppm); 8.02 (br s 1H), 7.73 (dt 1H J=8.0, 0.9Hz), 7.50 (dd 1H J=8.3, 0.9Hz), 7.32 (ddd 1H J=8.3, 7.0, 1.0Hz), 7.16 (ddd 1H J=8.0, 7.0, 1.0Hz), 7.09 (d 1H J=0.8Hz), 4.67 (dd 1H J=11.0, 9.3Hz), 4.57 (dd 1H J=11.0, 4.1Hz), 4.15 (m 1H), 3.99 (dd 1H J=10.1, 3.2Hz), 3.76 (s 3H), 3.64 (dd 1H J=10.1,8.3Hz), 1.67 (s 3H)

SI--MS m/z; 498, 500 (M+1)⁺

IR(KBr) ν_(max) (cm⁻¹); 3390, 3320, 1717, 1686, 1609, 1510

EXAMPLE 4 Synthesis of Compound 3

In an argon atmosphere, 7.0 mg (0.175 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide and 0.7 ml of a dimethyl formamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the solution at -10° C. Then the mixture was stirred at -15° to -5° C. for 50 minutes and 0.8 ml of a dimethylformamide solution containing 50 mg (0.161 mmol) of p-nitrophenyl 5-methoxyindole-2-carboxylate was dropwise added to the reaction mixture at -20° C. After stirring at -20° to -10° C. for 2 hours, the reaction mixture was treated in a conventional manner to give 91 mg of the crude product. The crude product was dissolved in 5 ml of methylene chloride and 40 μl of 48% hydrogen bromide aqueous solution was added to the solution followed by stirring at room temperature for 25 minutes. The reaction mixture was treated in the conventional manner to give the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-30:1) to give 24.7 mg of Compound 3 (yield; 32.0%).

Physicochemical properties of Compound 3 are as follows.

¹ H--NMR(CDCl₃ -CD30D) 6 (ppm); 7.99 (br s 1H), 7.36 (d 1H J=8.9Hz), 7.12 (d 1H J=2.3Hz), 7.01 (dd 1H J=8.9, 2.3Hz), 7.00 (d 1H J=0.6Hz), 4.63 (dd 1H J=10.9, 9.3Hz), 4.55 (dd 1H J=10.9, 4.3Hz), 4.16 (m 1H), 4.03 (dd 1H J=10.0, 3.3Hz), 3.87 (s 3H), 3.77 (s 3H), 3.59 (dd 1H J=10.0, 8.7Hz), 1.69 (s 3H)

SI--MS m/z; 528, 530(M+1)⁺

IR(KBr) ν_(max) (cm⁻¹); 3350(br), 1733, 1696, 1684, 1623, 1505

EXAMPLE 5 Synthesis of Compound 4

In an argon atmosphere, 7.0 mg (0.175 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide and 0.7 ml of a dimethylformamide solution containing 40 mg of Compound 18 was dropwise added to the solution at -20° to -10° C. After the mixture was stirred at -20° to -10° C. for one hour and 10 minutes, 0.8 ml of a dimethylformamide solution containing 45 mg of p-nitrophenyl benzofuran-2-carboxylate was dropwise added to the reaction mixture at -20° C. After stirring at -20° to -10° C. for 40 minutes, the reaction mixture was treated in the conventional manner. The obtained residue (82 mg) was dissolved in 14 ml of acetonitrile and 40 μl of 48% hydrogen bromide aqueous solution was added to the solution followed by stirring at room temperature for 25 minutes. The reaction mixture was treated in the conventional manner to give 88 mg of the residue. The residue was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; n-hexane: ethyl acetate=2:1) to give 40.8 mg of Compound 4 (yield; 53.2%).

Physicochemical properties of Compound 4 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 10.43 (br 1H), 8.56 (s 1H), 7.77 (m 1H), 7.70 (d 1H J=0.9Hz), 7.63 (dd 1H J=8.4, 0.8Hz), 7.49 (ddd 1H J=8.4, 7.2, 1.2Hz), 7.37 (ddd 1H J=8.0, 7.2, 0.8Hz), 4.75 (dd 1H J=11.9, 9.1Hz), 4.68 (dd 1H J=11.9, 4.4Hz), 4.16 (m 1H), 4.01 (dd 1H J=10.1, 3.2Hz), 3.79 (s 3H), 3.66 (dd 1H J=10.1, 8.3Hz), 1.72(s 3H)

SI--MS m/z; 499, 501 (M+1)⁺

IR(KBr) ν_(max) (cm⁻¹); 3360(br), 1740, 1702, 1696, 1602, 1508

EXAMPLE 6 Synthesis of Compound 5

DC-88A, 40 mg (0.079 mmol), was dissolved in 8 ml of acetonitrile and 40 μl of 57% hydrogen iodide aqueous solution was added to the solution followed by stirring at room temperature for 15 minutes. The reaction mixture was treated in the conventional manner to give 48 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel; eluting solvent; chloroform: acetone=1:0-30:1 ) to give 41.8 mg of Compound 5 (yield; 83.5%).

Physicochemical properties of Compound 5 are as follows.

¹ H--NMR(CDCl₃) δ (ppm); 9.57 (br 1H), 9.52 (br s 1H), 8.49 (s 1H), 7.01 (d 1H J=2.3Hz), 6.88 (s 1H), 4.62 (dd 1H J=10.9, 9.4Hz), 4.39 (dd 1H J=10.9, 4.4Hz), 4.15 (s 3H), 4.06 (m 1H), 3.96 (s 3H), 3.92 (s 3H), 3.84 (dd 1H J=9.9, 3.1Hz), 3.74 (s 3H), 3.48 (dd 1H J=9.9, 8.7Hz), 1.70 (s 3H)

SI--MS m/z; 636 (M+1)⁺, 510, 402

IR(KBr) ν_(max) (cm⁻¹); 3350(br), 1740, 1690, 1612, 1502

Example 7 Synthesis of Compound 6

In an argon atmosphere, 7.0 mg (0.175 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide and 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the solution at -20° C. After stirring at -20° to -10° C. for 30 minutes, 0.8 ml of a dimethylformamide solution of 35 mg (0.175 mmol) of N-trans-cinnamoylimidazole was dropwise added to the reaction mixture at -30° C. After stirring at -30 to -20° C. for 50 minutes, the reaction mixture was treated in the conventional manner to give 58 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel; eluting solvent; chloroform: acetone=1:0-50:1) to give 46.1 mg of Compound 6 (yield; 78.2%).

Physicochemical properties of Compound 6 are as follows.

¹ H--NMR(CDCl₃) δ (ppm); 7.84 (d 1H J=15.4Hz), 7.54-7.57 (m 2H) 7.40-7.45 (m 3H), 6.87 (br 1H), 6.78 (d 1H J=15.4Hz), 6.01 (br s 1H), 4.24 (d 1H J=11.0Hz), 4.18 (dd 1H J=11.0, 4.9Hz), 3.75 (s 3H), 2.99 (m 1H), 2.27 (dd 1H J=7.7, 3.9Hz), 1.66 (s 3H), 1.23 (dd 1H J=4.9, 4.0Hz)

SI--MS m/z; 405(M+1)⁺, 406(M+2)⁺, 407(M+3)⁺

IR(KBr) μ_(max) (cm⁻¹); 3300 (br), 1740, 1671, 1614, 1558

EXAMPLE 8 Synthesis of Compound 7

Compound 6, 33 mg, was dissolved in 4 ml of acetonitrile and 25 μl of 48% hydrogen bromide aqueous solution was added to the solution followed by stirring at room temperature for 15 minutes. The reaction mixture was treated in the conventional manner. The resulting crude product was purified by silica gel column chromatography (8 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 25.3 mg of Compound 7 (yield; 63.9%).

Physicochemical properties of Compound 7 are as follows.

¹ H--NMR(CDCl₃ -CD30D) δ (ppm); 8.06 (s 1H), 7.76 (d 1H J=15.4Hz), 7.60-7.62 (m 2H), 7.41-7.46 (m 3H), 6.87 (d 1H J=15.4Hz), 4.42 (dd 1H J=10.8, 9.8Hz), 4.31(dd 1H J=10.8, 4.3Hz), 4.13 (m 1H), 4.01 (dd 1H J=10.0, 3.2Hz), 3.76 (s 3H), 3.59 (dd 1H J=10.0, 8.7Hz), 1.67 (s 3H)

IR(KBr) ν_(max) (cm⁻¹); 1738, 1698, 1643, 1577, 1500

EI--MS m/z; 486, 484(M+), 404, 345, 274, 215

EXAMPLE 9 Synthesis of Compound 8

In an argon atmosphere, 7.0 mg (0.175 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide and 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the suspension at -20° C. After stirring at -20° to -10° C. for 2 hours, 0.7 ml of a dimethylformamide solution containing 19 μl (0.175 mmol) of phenyl isocyanate was dropwise added to the reaction mixture at -30° C. After stirring at -30 to -20° C. for 45 minutes, the reaction mixture was treated in the conventional manner. The resulting crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-20:1) to give 12.6 mg of Compound 8 (yield; 22.0%).

Physicochemical properties of Compound 8 are as follows.

¹ H--NMR(CDCl₃) δ (ppm); 7.40-7.43 (m 2H), 7.32-7.37 (m 2H) 7.15 (m 1H), 6.93 (br s 1H), 6.74 (s 1H), 6.03 (br s 1H), 4.17 (dd 1H J=10.6, 5.2Hz), 4.04 (d 1H J=10.6Hz), 3.75 (s 3H), 3.00 (ddd 1H J=7.7, 5.0, 5.0Hz), 2.22 (dd 1H J=7.7, 3.9Hz), 1.65 (s 3H), 1.21 (dd 1H J=4.9, 4.0Hz)

SI--MS m/z; 394(M+1)⁺, 395(M+2)⁺, 396(M+3)⁺

IR(KBr) νmax (cm⁻¹); 1734, 1670, 1530, 1442

EXAMPLE 10 Synthesis of Compound 9

In an argon atmosphere, 6.4 mg (0.161 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide and 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the suspension at -20° C. After stirring at -20° to -10° C. for 1.5 hours, 0.7 ml of a dimethylformamide solution of 16 μl (0.146 mmol) of phenylisocyanate was dropwise added to the reaction mixture at -30° C. After stirring at -30° to -20° C. for 30 minutes, 40 μl of 48% hydrogen bromide aqueous solution was added to the reaction mixture followed by stirring at -10 to 0° C. for 15 minutes. The reaction mixture was treated in the conventional manner to give 74 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; n-hexane: ethyl acetate=2:1) to give 22.2 mg of Compound 9 (yield; 32.1%).

Physicochemical properties of Compound 9 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 8.05 (s 1H), 7.32-7.37 (m 5H), 7.15 (m 1H), 6.49 (br 1H), 4.02-4.16 (m 4H), 3.76 (s 3H), 3.50 (m 1H), 1.66 (s 3H)

IR(KBr) νmax (cm⁻¹); 3370(br), 1732, 1634-1700, 1597, 1531, 1507

SI--MS m/z; 474, 476(M+1)⁺, 414, 416, 295, 297, 215

EXAMPLE 11 Synthesis of Compound 10

In an argon atmosphere, 7.0 mg (0.175 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide. While cooling the suspension at -20° C., 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -20° to -10° C. for 2 hours and 40 minutes. After cooling to -30° C., 0.7 ml of a dimethylformamide solution containing 17 μl (0.146 mmol) of benzoyl chloride was dropwise added to the reaction mixture. After stirring at -30° to -20° C. for 40 minutes, the reaction mixture was treated in the conventional manner to give 53 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 37.1 mg of Compound 10 (yield; 67.2%).

Physicochemical properties of Compound 10 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.51-7.57 (m 3H), 7.42-7.46 (m 2H), 5.94 (br s 1H), 5.89 (s 1H), 4.20 (dd 1H J=11.7, 5.0Hz), 4.10 (d 1H J=11.7Hz), 3.74 (s 3H), 2.98 (ddd 1H J=7.7, 5.0, 5.0Hz), 2.35 (dd 1H J=7.7, 3.9Hz), 1.64 (s 3H), 1.41 (dd 1H J=5.0, 3.9Hz)

SI--MS m/z; 381(M+3)⁺, 380(M+2)⁺, 379(M+1)⁺, 321

IR(KBr) ν_(max) (cm⁻¹); 3260, 1742, 1669, 1617, 1559

EXAMPLE 12 Synthesis of Compound 11

Compound 10, 31 mg, was dissolved in 1 ml of acetonitrile and 25 μl of 48% hydrogen bromide aqueous solution was added to the solution followed by stirring at room temperature for an hour. The reaction mixture was treated in the conventional manner. The resulting crude product was purified by silica gel column chromatography (8 ml of silica gel, eluting solvent; n-hexane: ethyl acetate=2:1) to give 20.7 mg of Compound 11 (yield; 55.0%).

Physicochemical properties of Compound 11 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 10.37 (br s 1H), 8.53 (br s 1H), 7.52-7.61 (m 5H), 5.17 (br 1H), 4.18 (dd 1H J=12.1, 9.8Hz), 3.97-4.03 (m 2H), 3.88 (dd 1H J=10.1, 31.1Hz), 3.73 (s 3H), 3.61 (dd 1H J=10.1, 7.7Hz), 1.65 (s 3H)

IR(KBr) ν_(max) (cm⁻¹); 3362, 3230, 1718, 1648, 1630, 1509, 1402

SI--MS m/z; 461, 459(M+1)⁺, 401, 399

EXAMPLE 13 Synthesis of Compound 12

In an argon atmosphere, 7.9 mg (0.197 mmol) of 60% sodium hydride was suspended in 0.7 ml of dimethylformamide. While cooling the suspension at -20° C., 0.8 ml of a dimethylformamide solution containing 45 mg (0.164 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -20° to -10° C. for 2 hours and 40 minutes. After cooling to -30° C., 0.8 ml of a dimethylformamide solution containing 22.3 μl (0.180 mmol) of benzyl isocyanate was dropwise added to the reaction mixture. After stirring at -30° C. for 30 minutes, the reaction mixture was treated in the conventional manner to give 59 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-20:1) to give 34.1 mg of Compound 12 (yield; 51.0%).

Physicochemical properties of Compound 12 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.30-7.38 (m 5H), 6.77 (s 1H), 6.00 (br s 1H), 5.29 (m 1H), 4.50 (dd 1H J=14.5, 5.6Hz), 4.48 (dd 1H J=14.5, 5.5Hz), 4.04 (dd 1H J=10.3, 5.2Hz), 3.94 (d 1H J=10.3Hz), 3.74 (s 3H), 2.95 (ddd 1H J=7.6, 5.0, 5.0Hz), 2.15 (dd 1H J=7.6, 3.9Hz), 1.63 (s 3H), 1.14 (dd 1H J=4.9, 3.9Hz)

SI--MS m/z; 410(M+3)⁺, 409(M+2)⁺, 408(M+1)⁺

IR(KBr) ν_(max) (cm⁻¹); 1746, 1664, 1611, 1527

EXAMPLE 14 Synthesis of Compound 13

In an argon atmosphere, 6.4 mg (0.161 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide. While cooling the suspension at -20° C., 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -20° to -10° C. for 2 hours and 10 minutes. After cooling to -30° C., 0.7 ml of a dimethylformamide solution containing 21.3 μl (0.161 mmol) of benzyl isothiocyanate was dropwise added to the reaction mixture. After stirring at -30° to -20° C. for 50 minutes, 40 μl of 48% hydrogen bromide aqueous solution was added to the reaction mixture followed by stirring at -20° C. to room temperature for 15 minutes. Citrate buffer of pH 5 was added and the formed precipitates were taken by filtration. After thoroughly washing with water, the precipitates were dried in vacuum to give 52.5 mg of Compound 13 (yield; 71.4%).

Physicochemical properties of Compound 13 are as follows.

¹ H--NMR(CDCl₃ -CD₃ OD) δ (ppm); 8.44 (s 1H), 7.28-7.41 (m 5H), 4.93 (d 1H J=14.9Hz), 4.92 (d 1H J=14.9Hz) 4.31 (dd 1H J=11.0, 91.1Hz), 4.26 (dd 1H J=11.0, 41.1Hz), 3.97 (m 1H), 3.94 (dd 1H J=9.7, 3.2Hz), 3.75 (s 3H), 3.53 (dd 1H J=9.7, 8.5Hz), 1.65 (s 3H)

SI--MS m/z; 506, 504(M+1)⁺, 399, 397, 356, 354, 297, 295

IR(KBr) ν_(max) (cm⁻¹); 3350, 1717, 1654, 1630, 1507

EXAMPLE 15 Synthesis of Compound 14

In an argon atmosphere, 6.4 mg (0.161 mmol) of 60% sodium hydride was suspended in 0.6 ml of dimethylformamide. While cooling the suspension to -20° C., 0.7 ml of a dimethylformamide solution containing 40 mg (0.146 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -20° to -10° C. for 2 hours. After cooling to -30° C., 0.7 ml of a dimethylformamide solution containing 20.2 μl (0.161 mmol) of phenoxyacetyl chloride was dropwise added to the reaction mixture. After stirring at -30° to -20° C. for 25 minutes, the reaction mixture was treated in the conventional manner to give 58 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform) to give 35.8 mg of Compound 14 (yield; 60.1%).

Physicochemical properties of Compound 14 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.31 (m 2H), 7.14 (br 1H), 7.03 (t 1H J=7.4Hz), 6.92 (m 2H), 6.00 (br s 1H), 4.75 (s 2H), 4.22 (d 1H J=10.8Hz), 4.13 (dd 1H J=10.8, 5.1Hz), 3.74 (s 3H), 2.97 (ddd 1H J=7.7, 5.1, 5.0Hz), 2.17 (dd 1H J=7.6, 4.0Hz), 1.65 (s 3H), 1.07 (dd 1H J=4.6, 4.0Hz)

SI--MS m/z; 411(M+3)⁺, 410(M+2)⁺, 409(M+1)⁺, 381, 351, 215

IR(KBr) ν_(max) (cm⁻¹); 1733, 1663, 1627, 1560

EXAMPLE 16 Synthesis of Compound 15

Compound 14, 23.5 mg, was dissolved in 0.8 ml of acetonitrile and 20 μl of 48% hydrogen bromide aqueous solution was added to the solution followed by stirring at room temperature for 10 minutes. The reaction mixture was treated in the conventional manner to give 27.4 mg of Compound (yield; 97.3%).

Physicochemical properties of Compound 15 are as follows:

¹ H--NMR(CDCl₃) δ(ppm); 8.43 (s 1H), 7.29 (m 2H), 7.02 (m 3H), 4.77 (d 1H J=14.3Hz), 4.74 (d 1H J=14.3Hz), 4.15 (m 1H), 4.05 (dd 1H J=10.9, 4.2Hz), 3.93-4.00 (m 2H), 3.82 (s 3H), 3.55 (dd 1H J=10.7, 8.9Hz), 1.69 (s 3H)

EI--MS m/z; 488, 490(M⁺), 429, 431, 408, 349

IR(KBr) ν_(max) (cm⁻¹); 3364, 1733, 1699, 1653, 1625, 1508

EXAMPLE 17 Synthesis of Compound 16

In an argon atmosphere, 8.0 mg (0.200 mmol) of 60% sodium hydride was suspended in 0.7 ml of dimethylformamide. While cooling the suspension at -20° C., 0.8 ml of a dimethylformamide solution containing 50 mg (0.182 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -20° to -10° C. for 2 hours and 25 minutes. After cooling to -30° C., 0.8 ml of a dimethylformamide solution containing 26 μl (0.182 mmol) of benzyl chloroformate was dropwise added to the reaction mixture. After stirring at -30° to -20° C. for 35 minutes, the reaction mixture was treated in the conventional manner to give 71 mg of the crude product. The crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform) to give 47.6 mg of Compound 16 (yield; 63.9%).

Physicochemical properties of Compound 16 are as follows.

¹ H--NMR(CDCl₃) δ (ppm); 7.34-7.41 (m 5H), 7.00 (br s 1H), 6.08 (br s 1H), 5.26 (s 2H), 4.08 (d 1H J=11.3Hz), 3.99 (dd 1H J=11.3, 5.2Hz), 3.73 (s 3H), 2.95 (ddd 1H J=7.7, 5.2, 4.9Hz), 2.13 (dd 1H J=7.7, 3.8Hz), 1.64 (s 3H), 1.15 (dd 1H J=4.9, 4.0Hz)

IR(KBr) ν_(max) (cm⁻¹); 3300(br), 1730, 1675, 1628, 1566, 1400

EI--MS m/z; 408(M⁺), 349

EXAMPLE 18 Synthesis of Compound 17

Compound 17 was obtained in 25.7 mg (yield; 33.5%) from 50 (0.182 mmol) of Compound 18 in a manner similar to Example 9 except for using 23 μl (0.182 mmol) of benzoyl isocyanate instead of phenyl isocyanate.

Physicochemical properties of Compound 17 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 8.25 (br s 1H), 7.82 (m 2H), 7.62(m 1H), 7.50 (m 2H), 6.62 (s 1H), 6.00 (br s 1H), 4.21 (dd 1H J=11.1, 4.9Hz), 4.11 (d 1H J=111.1Hz), 3.75 (s 3H), 2.97 (ddd 1H J=7.6, 5.0, 4.9Hz), 2.32 (dd 1H J=7.6, 3.8Hz), 1.64 (s 3H), 1.27 (m 1H)

EXAMPLE 19 Synthesis of Compound 19

Compound a, 48 mg, obtained in Reference Example 1 was dissolved in 0.5 ml of acetic acid and 0.4 ml of 25% hydrogen bromide/acetic acid was added to the solution followed by stirring at room temperature for an hour and 10 minutes. After the reaction solution was concentrated, ether was added to the residue. The mixture was ground, filtered and dried to give 38.6 mg of Compound 19 (yield; 87.9%).

Physicochemical properties of Compound 19 are as follows.

¹ H--NMR(CD₃ OD) δ(ppm); 8.21 (s 1H), 7.68-7.76 (m 5H), 4.75 (d 1H J=16.0Hz), 4.70 (d 1H J=16.0Hz), 4.41 (dd 1H J=10.1, 9.2Hz), 4.26 (m 1H), 4.21 (dd 1H J=10.2, 4.3Hz), 4.10 (dd 1H J=10.0, 2.9Hz), 3.93 (dd 1H J=10.0, 71.1Hz), 3.85 (s 3H), 1.74 (s 3H)

SI--MS m/z; 488, 490(M--HBr)⁺, 396, 398, 215

EXAMPLE 20 Synthesis of Compound 20

Compound 20 was obtained in 14.4 mg (yield: 67.1%) in a manner similar to Example 8 except for using 18 mg of Compound 17 instead of Compound 6.

Physicochemical properties of Compound 20 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.76-7.83 (m 2H), 7.63 (br s 1H) 7.51-7.56 (m 1H), 7.41-7.48 (m 2H), 4.27 (dd 1H J=10.8, 9.4Hz), 4.06 (dd 1H J=10.9, 41.1Hz), 3.99 (m 1H), 3.89 (dd 1H J=10.0, 3.2Hz), 3.69 (s 3H), 3.52 (dd 1H J=10.0, 8.4Hz), 1.59 (s 3H)

EI--MS m/z; 421(M--HBr)⁺, 354, 356, 295, 297, 274, 215, 147

EXAMPLE 21 Synthesis of Compound 21

Compound 21 was obtained in 138 mg (yield: 74.8%) from 160 mg (0.58 mmol) of Compound 18 in a manner similar to Example 2 except for using 41 μl (0.58 mmol) of acetyl chloride instead of indole-2-carbonyl chloride.

Physicochemical properties of Compound 21 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 6.9-7.1 (br 1H), 5.98 (br s 1H) 4.10 (d 1H J=10.8Hz), 4.03 (dd 1H J=10.8, 4.9Hz), 3.74 (s 3H), 2.96 (m 1H), 2.27 (s 3H), 2.19 (dd 1H J=7.6, 3.9Hz), 1.65 (s 3H), 1.14 (dd 1H J=4.8, 3.9Hz)

EI--MS m/z; 316(M⁺), 274, 257, 215

EXAMPLE 22 Synthesis of Compound 22

Compound 22 was obtained in 130 mg (yield: 64.7%) in a manner similar to Example 8 except for using 160 mg of Compound 21 instead of Compound 6.

Physicochemical properties of Compound 22 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 10.70 (br s 1H), 8.42 (s 1H), 5.35 (s 1H), 4.22 (dd 1H J=10.0, 8.6Hz), 4.08 (m 1H), 4.05 (m 1H), 4.02 (dd 1H J=10.2, 31.1Hz), 3.78 (s 3H), 3.54 (dd 1H J=9.8, 8.5Hz), 2.32 (s 3H), 1.69 (s 3H)

EI--MS m/z; 396, 398(M⁺), 337, 339, 316, 257, 215

EXAMPLE 23 Synthesis of Compound 23

Compound 23 was obtained in 27.5 mg (yield: 52.7%) from 30 mg (0.109 mmol) of Compound 18 in a manner similar to Example 2 except for using 37.4 mg (0.109 mmol) of p-nitrophenyl 5,6-dimethoxyindole-2-carboxylate instead of indole-2-carbonyl chloride.

Physicochemical properties of Compound 23 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 9.21 (br 1H), 7.23 (br s 1H), 7.01(s 1H), 6.95 (br s 1H), 6.86 (s 1H), 6.06 (br 1H), 4.43 (m 2H), 3.95 (s 3H), 3.92 (s 3H), 3.75 (s 3H), 3.06 (m 1H), 2.23 (dd 1H J=7.6, 3.9Hz), 1.67 (s 3H), 1.27 (dd 1H J=4.8, 4.0Hz)

EI--MS m/z; 477(M⁺), 407, 288, 227, 215, 213, 204

EXAMPLE 24 Synthesis of Compound 24

Compound 24 was obtained in 16.5 mg (yield: 94.1%) in a manner similar to Example 8 except for using 15 mg of Compound 23 instead of Compound 6.

Physicochemical properties of Compound 24 are as follows.

¹ H--NMR(CDCl₃ -CD₃ OD) δ(ppm); 7.99 (s 1H), 7.11 (s 1H), 6.99 (s 1H), 6.95 (s 1H), 4.63 (dd 1H J=10.9, 9.3Hz), 4.54 (dd 1H J=10.9, 4.2Hz), 4.16 (m 1H), 4.01 (dd 1H J=10.0, 3.3Hz), 3.96 (s 3H), 3.94 (s 3H), 3.77 (s 3H), 3.59 (dd 1H J=10.0, 8.6Hz), 1.68(s 3H)

EI--MS m/z; 557, 559(M⁺), 477, 354, 356, 274, 213, 204

EXAMPLE 25 Synthesis of Compound 25

Compound 25 was obtained in 37.3 mg (yield: 58.9%) from 40 mg (0.146 mmol) of Compound 18 in a manner similar to Example 2 except for using 46 mg (0.153 mmol) of p-nitrophenyl benzothiophene-2-carboxylate instead of indole-2-carbonyl chloride.

Physicochemical properties of Compound 25 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.83-7.88 (m 2H), 7.79 (d 1H J=0.7Hz), 7.48 (m 1H), 7.43 (m 1H), 6.60 (s 1H), 5.98 (br s 1H), 4.37 (dd 1H J=11.1, 5.0Hz), 4.27 (d 1H J=111.1Hz), 3.75 (s 3H), 3.02 (dt 1H J=7.7, 4.9Hz), 2.34 (dd 1H J=7.7, 3.9Hz), 1.66 (s 3H), 1.40 (dd 1H J=4.9, 41.1Hz)

EI--MS m/z; 434(M⁺), 375, 161

Synthesis of Compound 26

Compound 26 was obtained in 26.7 mg (yield: 86.6%) in a manner similar to Example 8 except for using 26 mg of Compound 25 instead of Compound 6.

Physicochemical properties of Compound 26 are as follows.

¹ H--NMR(CDCl₃ -CD₃ OD) δ(ppm); 7.90-7.93 (m 3H), 7.82 (s 1H), 7.43-7.50 (m 2H), 4.58 (dd 1H J=11.1, 9.2Hz), 4.47 (dd 1H J=11.1, 41.1Hz), 4.11 (m 1H), 3.97 (m 1H), 3.76 (s 3H), 3.64 (dd 1H J=10.1, 8.2Hz), 1.68 (s 3H)

EI--MS m/z; 514, 516(M⁺), 434(M--HBr)⁺, 375, 161

EXAMPLE 27 Synthesis of Compound 27

Compound 27 was obtained in 50.1 mg (yield: 79.1%) from 40 mg (0.146 mmol) of Compound 18 in a manner similar to Example 2 except for using 46 mg (0.153 mmol) of p-nitrophenyl 3-methoxycinnamate instead of indole-2-carbonyl chloride.

Physicochemical properties of Compound 27 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.80 (d 1H J=15.4Hz), 7.33 (dd 1H J=8.0, 7.9Hz), 7.16 (br d 1H J=7.6Hz), 7.05 (m 1H), 6.97 (ddd 1H J=8.2, 2.6, 0.8Hz), 6.89 (br 1H), 6.75 (d 1H J=15.4Hz), 6.01 (br s 1H), 4.23 (d 1H J=11.0Hz), 4.18 (dd 1H J=11.0, 4.9Hz), 3.85 (s 3H), 3.75 (s 3H), 2.99 (m 1H), 2.26 (dd 1H J=7.7, 3.9Hz), 1.66 (s 3H), 1.23 (m 1H)

EI--MS m/z; 434(M+), 375, 274, 161

EXAMPLE 28 Synthesis of Compound 28

Compound 28 was obtained in 24.1 mg (yield: 78.1%) in a manner similar to Example 8 except for using 26 mg of Compound 27 instead of Compound 6.

Physicochemical properties of Compound 28 are as follows.

¹ H--NMR(CD₃ OD) δ(ppm); 8.12 (s 1H), 7.66 (d 1H J=15.4Hz), 7.33 (dd 1H J=7.9, 7.8Hz), 7.25 (br d 1H J=7.8Hz), 7.22 (br s 1H), 7.06 (d 1H J=15.4 Hz), 6.97 (m 1H), 4.49 (dd 1H J=11.0, 9.9Hz), 4.32 (dd 1H J=11.0, 4.3Hz), 4.09 (m 1H), 3.93 (dd 1H J=10.0, 3.0Hz), 3.85 (s 3H), 3.79 (dd 1H J=9.9, 7.2Hz), 3.69 (s 3H) 1.57(s 3H)

EXAMPLE 29 Synthesis of Compound 29

Compound 29 was obtained in 49.1 mg (yield: 72.5%) from 40 mg (0.146 mmol) of Compound 18 in a manner similar to Example 2 except for using 50 mg (0.153 mmol) of p-nitrophenyl 3,4-dimethoxycinnamate instead of indole-2-carbonyl chloride.

Physicochemical properties of Compound 29 are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 7.79 (d 1H J=15.3Hz), 7.18 (dd 1H J=8.4, 2.0Hz), 7.04 (d 1H J=2.0Hz), 6.89 (br 1H), 6.89 (d 1H J=8.4Hz), 6.62 (d 1H J=15.3Hz), 6.01 (br s 1H), 4.23 (d 1H J=11.0Hz), 4.18 (dd 1H J=11.0, 4.8Hz), 3.934 (s 3H), 3.926 (s 3H), 3.75 (s 3H), 2.99 (m 1H), 2.26 (dd 1H J=7.6, 3.9Hz), 1.66 (s 3H), 1.23 (dd 1H J=5.0, 3.9Hz)

EI--MS m/z; 464(M⁺), 406, 191

EXAMPLE 30 Synthesis of Compound 30

Compound 30 was obtained in 17.3 mg (yield: 52.6%) in a manner similar to Example 8 except for using 28 mg of Compound 29 instead of Compound 6.

Physicochemical properties of Compound 30 are as follows.

¹ H--NMR(CD₃ OD) δ(ppm); 8.12 (s 1H), 7.64 (d 1H J=15.4Hz), 7.31 (d 1H J=1.7Hz), 7.23 (dd 1H J=8.4, 1.9Hz), 6.99 (d 1H J=8.4Hz), 6.93 (d 1H J=15.4Hz), 4.48 (dd 1H J=11.0, 10.2Hz), 4.32 (dd 1H J=11.0, 4.3Hz), 4.08 (m 1H), 3.92 (dd 1H J=10.0, 3.0Hz), 3.79 (dd 1H J=9.9, 7.2Hz), 3.90 (s 3H), 3.87 (s 3H), 3.69 (s 3H), 1.57 (s 3H)

EI--MS m/z; 544, 546(M⁺), 464, 405, 191

EXAMPLE 31 Synthesis of Compound 31

Compound 31 was obtained in 48.6 mg (yield: 100%) in a manner similar to Example 19 except for using 53 mg of Compound b obtained in Reference Example 2 instead of Compound a.

Physicochemical properties of Compound 31 are as follows.

¹ H--NMR(DMSO-d₆) δ(ppm); 10.16 (br s 1H), 8.00 (s 1H), 7.25 (br 1H), 7.03 (d 1H J=71.1Hz), 6.95 (dd 1H J=7.4, 71.1Hz), 6.56-6.60 (m 2H), 4.64 (dd 1H J=10.5, 5.8Hz), 4.39 (m 1H), 4.00-4.06(m 2H) 3.94(dd 1H J=9.7,2.6Hz) 3.80(dd 1H J=9.6,7.2Hz) 3.59(s 3H) 3.48(m 1H) 3.23(m 1H) 1.45(s 3H)

EI--MS m/z: 499, 501, 419, 360, 356, 274, 215

EXAMPLE 32 Synthesis of Compound 32

In an argon atmosphere, 8.7 mg (0.22 mmol) of 60% sodium hydride was suspended in 0.8 ml of dimethylformamide. While cooling the suspension to -30° C. and 0.7 ml of a dimethylformamide solution containing 50 mg (0.18 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -30° to -10° C. for 2 hours. After cooling to -50° C., 1.2 ml of a dimethylformamide solution containing 80 mg (0.20 mmol) of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate was dropwise added to the reaction mixture. The mixture was stirred at -50° to -30° C. for 50 minutes. The reaction mixture was treated in the conventional manner and the resulting crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 54.2 mg of Compound 32 (yield: 55.8%).

Physicochemical properties of Compound 32 are as follows.

¹ H--NMR(DMSO-d₆) δ(ppm); 11.68 (br s 1H), 9.16 (br 1H), 8.70 (s 1H), 7.79 (br s 1H), 7.34 (br s 2H), 7.12 (d 1H J=2.0Hz), 6.93 (s 1H), 4.57 (dd 1H J=10.6, 5.3Hz), 4.43 (d 1H J=10.6Hz), 3.61 (s 3H), 3.01 (m 1H), 1.96 (dd 1H J=7.6, 3.6Hz), 1.49 (s 9H), 1.46 (s 3H), 1.43 (dd 1H J=4.8, 3.8Hz).

SI--MS m/z; 535 (M+3)⁺, 479

EXAMPLE 33 Synthesis of Compound 33

Compound 33 was obtained in 93 mg (yield: 88.9%) from 125 mg of Compound 32 in a manner similar to Example 8 except for using Compound 32 instead of Compound 6.

Physicochemical properties of Compound 33 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 11.21 (br s 1H), 10.17 (s 1H), 8.07 (br s 1H), 7.31 (s 1H), 7.20 (d 1H J=8.7Hz), 6.81 (d 1H J=1.7Hz), 6.77 (d 1H J=1.8Hz), 6.68 (dd 1H J=8.7, 21.1Hz), 4.79 (br 2H), 4.65 (dd 1H J=10.8, 9.7Hz), 4,33 (dd 1H J=11.0, 4.2Hz), 4.07 (m 1H), 3.93 (dd 1H J=9.6, 2.8Hz), 3.82 (dd 1H J=9.7, 7.2Hz), 3.61 (s 3H), 1.47 (s 3H).

SI--MS m/z; 513, 515 (M+1)⁺

EXAMPLE 34 Synthesis of Compound 34

In an argon atmosphere, 4.4 mg (0.11 mmol) of 60% sodium hydride was suspended in 0.5 ml of dimethylformamide. While cooling the suspension to -30° C., 0.5 ml of a dimethylformamide solution containing 25 mg (0.091 mmol) of Compound 18 was dropwise added to the suspension. The mixture was stirred at -30° to -10° C. for 2 hours. After cooling to -50° C., 0.5 ml of a dimethylformamide solution containing 29 mg (0.091 mmol) of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate was dropwise added to the reaction mixture. After stirring at -50° to -30° C. for 40 minutes, 0.025 ml of 47% hydrogen bromide aqueous solution was added to the mixture followed by stirring for further 20 minutes. The reaction mixture was treated in the conventional manner and the resulting crude product was purified by silica gel column chromatography (10 ml of silica gel, eluting solvent; chloroform: acetone=1:0-50:1) to give 37.8 mg of Compound 34 (yield: 78.3%).

Physicochemical properties of Compound 34 are as follows.

¹ H--NMR (CD₃ OD) δ(ppm); 8.09 (br 1H), 7.55 (s 1H), 7.54 (d 1H J=9.2 Hz), 7.26 (d 1H J=2.5Hz), 7.09 (dd 1H J=9.2, 2.6Hz), 4.71 (dd 1H J=11.2, 9.6Hz), 4.51 (dd 1H J=11.6, 4.0Hz), 4.12 (m 1H), 3.94 (dd 1H J=9.9, 3.0Hz), 3.85 (s 3H), 3.81 (dd 1H J=9.9, 7.3Hz), 3.68 (s 3H), 1.56 (s 3H).

EI--MS m/z; 528 530 (M⁺), 448 (M--HBr)⁺, 389 (M--HBr--CO₂ CH₃)⁺, 212, 175

IR (KBr) ν_(max) (cm⁻¹); 1741, 1700, 1653, 1502, 1420

EXAMPLE 35 Synthesis of Compound 35

Compound 35 was obtained in 53.7 mg (yield: 67.8%) from 40 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 3-acetoxycinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 35 are as follows.

¹ H--NMR (CDCl₃) δ (ppm); 10.83 (br s 1H), 8.52 (s 1H), 7.71 (d 1H J=15.6Hz), 7.35-7.37 (m 3H), 7.13 (dd 1H J=5.9, 2.7Hz), 6.81 (d 1H J=15.6Hz), 5.50 (s 1H), 4.29 (dd 1H J=10.3, 9.9Hz), 4.19 (dd 1H J=10.8, 4.2Hz), 3.97-4.02 (m 2H), 3.80 (s 3H), 3.56 (dd 1H J=10.3, 9.6Hz), 2.33 (s 3H), 1.69 (s 3H).

EI--MS m/z; 542 544 (M⁺), 462 (M--HBr)⁺, 403 (M--HBr--CO₂ CH₃)⁺, 354, 356, 274, 212, 214, 147

IR (KBr) δ_(max) (cm⁻¹); 1740, 1696, 1646, 1584, 1503, 1418.

EXAMPLE 36 Synthesis of Compound 36

Compound 36 was obtained in 68.8 mg (yield: 74.4%) from 40 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-carbobenzoxyaminocinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 36 are as follows.

¹ H--NMR (CDCl₃) δ (ppm); 10.62 (br 1H), 8.57 (s 1H), 7.74 (d 1H J=15.5Hz), 7.57 (d 2H J=8.7Hz), 7.45 (d 2H J=8.6Hz), 7.34-7.43 (m 5H), 6.85 (s 1H), 6.78 (d 1H J=15.5Hz), 5.30 (s 1H), 5.22 (s 2H), 4.39 (dd 1H J=10.5, 9.8Hz), 4.28 (dd 1H J=10.8, 4.3Hz), 4.10 (m 1H), 4.03 (dd 1H J=10.0, 3.2Hz), 3.77 (s 3H), 3.56 (dd 1H J=9.8, 8.9Hz), 1.69 (s 3H).

EI--MS m/z; 633, 635 (M⁺), 553 (M--HBr)⁺, 525, 527, 445, 386, 274, 212, 172

IR(KBr) ν_(max) (cm⁻¹); 3350, 1732, 1697, 1636, 1605, 1589, 1521, 1505, 1414.

EXAMPLE 37 Synthesis of Compound 37

Compound 37 was obtained in 31.0 mg (yield: 62.7%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-acetamidocinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 37 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 10.15 (s 1H), 10.10 (s 1H), 8.16 (s 1H), 7.70 (d 2H J=8.7Hz), 7.64 (d 2H J=8.7Hz), 7.55 (d 1H J=15.3Hz), 7.27 (s 1H), 7.00 (d 1H J=15.3Hz), 4.47 (dd 1H J=10.5, 101.1Hz) 4.21 (dd 1H J=10.9, 4.3Hz), 4.06 (m 1H), 3.91 (dd 1H J=9.7, 2.9Hz), 3.78 (dd 1H J=9.2, 8.3Hz), 3.60 (s 3H), 2.07 (s 3H), 1.46 (s 3H).

EI--MS m/z; 541, 543 (M⁺), 461 (M--HBr)⁺, 402 (M--HBr--CO₂ CH₃)+, 272, 212, 188

IR (KBr) ν_(max) (cm⁻¹); 3344, 1734, 1678, 1639, 1594, 1506, 1410, 1318, 1260.

EXAMPLE 38 Synthesis of Compound 38

Compound 38 was obtained in 32.6 mg (yield: 69.4%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-methoxycinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 38 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 10.84 (br s 1H), 8.59 (s 1H), 7.76 (d 1H J=15.5Hz), 7.58 (d 2H J=8.8Hz), 6.94 (d 2H J=8.8Hz), 6.73 (d 1H J=15.5Hz), 5.31 (s 1H), 4.39 (dd 1H J=10.6, 9.5Hz), 4.28 (dd 1H J=10.7, 4.3Hz), 4.08 (m 1H), 4.04 (dd 1H J=9.6, 3.2Hz), 3.87 (s 3H), 3.78 (s 3H), 3.55 (dd 1H J=9.6, 8.9Hz), 1.69 (s 3H).

EI--MS m/z; 514, 516 (M⁺), 434 (M--HBr)⁺, 375 (M--HBr--CO₂ CH₃)⁺, 354, 356, 161, 133.

IR (KBr) ν_(max) (cm⁻¹); 3354, 1742, 1698, 1635, 1602, 1508, 1434, 1305, 1251, 1173.

EXAMPLE 39 Synthesis of Compound 39

Compound 39 was obtained in 34.0 mg (yield: 68.1%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 3-(3,4-dimethoxyphenyl)propionate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 39 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 10.63 (br s 1H), 8.50 (s 1H), 6.82 (s 2H), 6.78 (s 1H), 5.27 (br s 1H), 4.05 (t 1H J=9.9Hz), 3.92-4.00 (m 2H), 3.87 (m 1H), 3.86 (s 3H), 3.81 (s 3H), 3.76 (s 3H), 3.31 (dd 1H J=9.6, 8.7Hz), 3.06 (t 2H J=7.6Hz), 2.74-2.88 (m 2H), 1.68 (s 3H).

EI--MS m/z; 546, 548 (M⁺), 466 (M--HBr)⁺, 407 (M--HBr--CO₂ CH₃)⁺, 315, 274, 215, 151.

IR (KBr) ν_(max) (cm⁻¹); 3340, 1743, 1695, 1608, 1508, 1433, 1262.

EXAMPLE 40 Synthesis of Compound 40

Compound 40 was obtained in 28.2 mg (yield: 58.6%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using 2,4,5-trichlorophenyl 4-dimethylaminocinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 40 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 10.11 (br s 1H), 8.17 (br 1H), 7.58 (d 2H J=8.9Hz), 7.52 (d 1H J=15.2Hz), 7.22 (br s 1H), 6.80 (d 1H J=15.2Hz), 6.73 (d 2H J=8.9Hz), 4.45 (dd 1H J=10.1, 10.0Hz), 4.18 (dd 1H J=10.9, 4.4Hz), 4.05 (m 1H), 3.91 (dd 1H J=9.7, 2.9Hz), 3.79 (dd 1H J=9.7, 7.6Hz), 3.60 (s 3H), 2.99 (s 6H), 1.46 (s 3H).

EM--MS m/z; 527, 529 (M⁺), 447 (M--HBr)⁺, 388 (M--HBr--CO₂ CH₃)⁺, 174.

EXAMPLE 41 Synthesis of Compound 41

Compound 41 was obtained in 30.7 mg (yield: 63.5%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-nitrocinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 41 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 10.18 (s 1H), 8.26 (d 2H J=8.8Hz), 8.16 (s 1H), 8.07 (d 2H J=8.8Hz), 7.71 (d 1H J=15.4Hz), 7.37 (d 1H J=15.4Hz), 7.33 (s 1H), 4.52 (dd 1H J=10.7, 10.0Hz), 4.27 (dd 1H J=11.1, 4.5Hz), 4.08 (m 1H), 3.92 (dd 1H J=9.7, 2.8Hz), 3.79 (dd 1H J=9.7, 7.7Hz), 3.60 (s 3H), 1.46 (s 3H).

EI--MS m/z; 529, 531 (M⁺), 470, 472 (M-CO₂ CH₃)⁺, 449 (M--HBr)⁺, 390 (M--HBr--CO₂ CH₃)⁺, 274, 215, 176, 146.

IR (KBr) ν_(max) (cm⁻¹); 3364, 1740, 1698, 1646, 1595, 1506, 1435, 1343, 1251.

EXAMPLE 42 Synthesis of Compound 42

Compound 42 was obtained in 33.2 mg (yield: 71.0%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-formylcinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate

Physicochemical properties of Compound 42 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 10.19 (s 1H), 10.04 (s 1H), 8.16 (s 1H), 8.01 (d 2H J=8.3Hz), 7.95 (d 2H J=8.3Hz), 7.68 (d 1H J=15.4Hz), 7.33 (br s 1H), 7.32 (d 1H J=15.4Hz), 4.52 (dd 1H J=10.7, 10.0Hz), 4.27 (dd 1H J=11.0, 4.5Hz), 4.08 (m 1H), 3.91 (dd 1H J=9.6, 2.8Hz), 3.80 (dd 1H J=9.6, 7.6Hz), 3.60 (s 3H), 1.46 (s 3H).

EI--MS m/z; 512, 514 (M⁺), 432 (M--HBr)⁺, 373 (M--HBr--CO₂ CH₃)⁺, 274, 215, 159.

IR (KBr) ν_(max) (cm⁻¹); 3360, 1734, 1698, 1635, 1601, 1502, 1432.

EXAMPLE 43 Synthesis of Compound 43

Compound 43 was obtained in 34.1 mg (yield: 65.0%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 3,4,5-trimethoxycinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 43 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 10.15 (br s 1H), 8.16 (br s 1H), 7.56 (d 1H J=15.3Hz), 7.28 (br s 1H), 7.09 (s 2H), 7.05 (d 1H J=15.3Hz), 4.50 (dd 1H J=10.5, 101.1Hz), 4.21 (dd 1H J=10.9, 4.3Hz), 4.10 (br 1H), 3.90 (dd 1H J=9.9, 3.0Hz), 3.86 (s 6H) (1H overlapped), 3.71 (s 3H), 3.60 (s 3H), 1.46 (s 3H).

EI--MS m/z; 574, 576 (M⁺), 494 (M--HBr)⁺, 435 (M--HBr--CO₂ CH₃)⁺, 354, 356, 221.

EXAMPLE 44 Synthesis of Compound 44

Compound 44 was obtained in 24.1 mg (yield: 50.9%) from 25 mg of Compound 18 in a manner similar to Example 34 except for using p-nitrophenyl 4-chlorocinnamate instead of p-nitrophenyl 5-methoxybenzofuran-2-carboxylate.

Physicochemical properties of Compound 44 are as follows.

EI--MS m/z; 518, 520 (M⁺), 438 (M--HBr)⁺, 379 (M--HBr--CO₂ CH₃)⁺, 274, 215, 165.

EXAMPLE 45 Synthesis of Compound 45

Compound 33, 25 mg (0.049 mmol), was dissolved in 4 ml of acetonitrile and 21 mg (0.074 mmol) of p-nitrophenyl indole-2-carboxylate and 4 mg of 4-dimethylaminopyridine were added to the solution followed by stirring at room temperature for 24 hours. After adding 5 mg of p-nitrophenyl indole-2-carboxylate to the reaction mixture, the mixture was stirred for further 3 hours and 30 minutes. The reaction mixture was treated in the conventional manner. The resulting crude product was purified by silica gel column chromatography (15 ml of silica gel, eluting solvent; chloroform: acetone=1:0-100:1) to give 19.3 mg of Compound 45 (yield: 60.4%).

Physicochemical properties of Compound 45 are as follows.

¹ H--NMR (CD₃ OD) δ(ppm); 8.50 (br s 1H), 7.70 (d 1H J=8.2Hz), 7.49 (dd 1H J=8.3, 0.9Hz), 7.48 (t 1H J=0.9Hz), 7.32 (ddd 1H J=8.3, 7.1, 11.1Hz), 7.28 (d 1H J=8.7Hz), 7.13 (ddd 1H J=8.0, 7.1, 1.0Hz), 7.03 (dd 1H J=2.1, 0.5Hz), 6.93 (s 1H), 6.85 (dd 1H J=8.7, 21.1Hz), 4.69 (dd 1H J=11.0, 9.6Hz), 4.55 (dd 1H J=11.0, 4.4Hz), 4.20 (m 1H), 3.96 (dd 1H J=10.1, 3.1Hz), 3.84 (dd 1H J=10.1, 7.2Hz), 3.71 (s 3H), 1.59 (s 3H).

SI--MS m/z; 656, 658 (M+1)⁺

IR (KBr) ν_(max) (cm⁻¹); 3344, 1715 (br), 1617, 1523, 1490, 1408, 1238, 1176.

EXAMPLE 46 Synthesis of Compound 46

Compound 46 was obtained in 26.0 mg (yield: 67.7%) from 16.5 mg of Compound 33 in a manner similar to Example 45 except for using p-nitrophenyl benzofuran-2-carboxylate instead of p-nitrophenyl indole-2-carboxylate.

Physicochemical properties of Compound 46 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 9.23 (br 1H), 8.64 (s 1H), 7.81 (d 1H J=0.9Hz), 7.77 (m 1H), 7.65 (dd 1H J=8.5, 0.8Hz), 7.54 (ddd 1H J=8.4, 7.3, 1.3Hz), 7.38 (ddd 1H J=8.0, 7.3, 0.9Hz), 7.27 (d 1H J=8.6Hz), 6.96 (d 1H J=21.1Hz), 6.88 (d 1H J=1.4Hz), 6.81 (dd 1H J=8.7, 2.2Hz), 5.32 (s 1H), 4.66 (dd 1H J=10.8, 9.3Hz), 4.61 (dd 1H J=10.8, 4.6Hz), 4.26 (m 1H), 4.05 (dd 1H J=10.1, 3.3Hz), 3.79 (s 3H), 3.66 (dd 1H J=10.0, 8.7Hz), 1.70 (s 3 H).

SI--MS m/z; 657, 659 (M+1)⁺, 498, 500 (M+1-CO₂ CH₃)⁺.

IR (KBr) ν_(max) (cm⁻¹); 3370, 1741, 1629, 1521, 1491, 1411, 1293, 1170.

EXAMPLE 47 Synthesis of Compound 47

Compound 47 was obtained in 19.3 mg (yield: 57.7%) from 25 mg of Compound 33 in a manner similar to Example 45 except for using p-nitrophenyl 5-methoxyindole-2-carboxylate instead of p-nitrophenyl indole-2-carboxylate.

Physicochemical properties of Compound 47 are as follows.

SI--MS m/z; 686 688 (M+1)⁺

IR (KBr) ν_(max) (cm⁻¹); 3344, 1717, 1623, 1525, 1491, 1420, 1209, 1179.

EXAMPLE 48 Synthesis of Compound 48

Compound 36, 30 mg, was dissolved in 1 ml of acetic acid and 0.2 ml of 25% hydrogen bromide/acetic acid was added to the solution. The mixture was stirred at room temperature for 4 hours and 30 minutes. The reaction solution was concentrated and the residue was treated in the conventional manner. The resulting crude product was purified by silica gel column chromatography (10 ml of silica gel; eluting solvent; chloroform: acetone=1:0-10:1) to give 18.9 mg (yield: 79.9%) of Compound 48.

Physicochemical properties of Compound 48 are as follows.

SI--MS m/z; 500, 502 (M+1)⁺

IR (KBr) ν_(max) (cm⁻¹): 3372, 1734, 1700, 1628, 1603, 1502, 1437, 1261.

EXAMPLE 49 Synthesis of Compound 49

Compound 49 was obtained in 14.2 mg (yield: 44.2%) from 25 mg of Compound 48 in a manner similar to Example 45 except for using Compound 48 instead of Compound 33.

Physicochemical properties of Compound 49 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 12.17 (br s 1H), 8.50 (br s 1H), 7.93 (s 1H), 7.74 (d 1H J=7.9Hz), 7.46-7.54 (m 3H), 7.45 (d 2H J=8.5Hz), 7.33 (t 1H J=7.2Hz), 7.14 (t 1H J=7.2Hz), 6.75 (d 1H J=15.2Hz), 6.58 (d 2H J=8.5Hz), 5.69 (br s 2H), 4.53 (dd 1H J=10.0, 9.9Hz), 4.27 (m 1H), 4.23 (m 1H), 3.96 (m 2H), 3.62 (s 3H), 1.48 (s 3H).

SI--MS m/z; 643, 645 (M+1)⁺

IR (KBr) ν_(max) (cm⁻¹); 3364, 1733 (br), 1635, 1594, 1516, 1490, 1433, 1309, 1263, 1175, 1144.

EXAMPLE 50 Synthesis of Compound 50

Compound 50 was obtained in 14.8 mg (yield: 42.9%) from 25 mg of Compound 48 in a manner similar to Example 45 except for using p-nitrophenyl 3,4-dimethoxycinnamate instead of p-nitrophenyl indole-2-carboxylate and using Compound 48 instead of Compound 33.

Physicochemical properties of Compound 50 are as follows.

¹ H--NMR (CDCl₃) δ (ppm); 8.58 (br 1H), 7.89 (d 1H J=15.9Hz), 7.74 (d 1H J=15.2Hz), 7.43 (d 2H J=8.5Hz), 7.20 (dd 1H J=8.4, 1.9Hz), 7.13 (d 1H J=1.9Hz), 6.92 (d 1H J=8.4Hz), 6.68 (d 2H J=8.5Hz), 6.62 (d 1H J=15.2Hz), 6.52 (d 1H J=15.9Hz), 5.20 (s 1H), 4.42 (dd 1H J=10.5, 9.7Hz), 4.34 (dd 1H J=10.7, 4.5Hz), 4.19 (m 1H), 4.05 (dd 1H J=9.9, 3.2Hz), 3.96 (s 3H), 3.95 (s 3H), 3.78 (s 3H), 3.58 (dd 1H J=9.7, 9.4 Hz), 1.67 (s 3H).

EXAMPLE 51 Synthesis of Compound 51

Compound 51 was obtained in 37.3 mg (yield: 72.7%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 4-(indole-2-carbonylamino) cinnamate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 51 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 11.76 (d 1H J=1.7Hz), 10.39 (s 1H), 8.68 (s 1H), 7.92 (d 2H J=8.8Hz), 7.81 (d 2H J=8.8Hz), 7.69 (d 1H J=15.3Hz), 7.69 (m 1H), 7.48 (dd 1H J=8.3, 0.8Hz), 7.46 (d 1H J=2.2Hz), 7.24 (ddd 1H J=8.2, 7.0, 1.2Hz), 7.13 (br 1H), 7.08 (ddd 1H J=7.9, 7.0, 0.9Hz), 7.00 (d 1H J=15.4Hz), 4.41 (d 1H J=10.7Hz), 4.30 (dd 1H J=10.6, 5.3Hz), 3.61 (s 3H), 3.01 (ddd 1H J=7.6, 5.1, 5.0Hz), 1.93 (dd 1H J=7.6, 3.5Hz), 1.46 (s 3H), 1.32 (dd 1H J=4.7, 3.6Hz).

SI--MS m/z; 565 (M+3)⁺

EXAMPLE 52 Synthesis of Compound 52

Compound 52 was obtained in 29.8 mg (yield: 70.9%) from 20 mg of Compound 18 in a manner similar to Example 32 except for using 2,4,5-trichlorophenyl 5-(indole-2-carbonylamino)benzofuran-2-carboxylate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 52 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 11.74 (d 1H J=1.6Hz), 10.36 (s 1H), 8.73 (s 1H), 8.35 (d 1H J=2.0Hz), 7.87 (dd 1H J=9.0, 21.1Hz), 7.86 (s 1H), 7.73 (d 1H J=9.0Hz), 7.69 (d 1H J=7.9Hz), 7.49 (dd 1H J=8.2, 0.6Hz), 7.44 (d 1H J=1.6Hz), 7.23 (m 1H), 7.08 (m 1H), 6.94 (s 1H), 4.55 (m 2H), 3.62 (s 3H), 3.05 (m 1H), 1.98 (dd 1H J=7.6, 3.6Hz), 1.47 (s 3H) (1H overlapped).

SI--MS m/z; 579 (M+3)⁺

IR(KBr) ν_(max) (cm⁻¹); 1734, 1652, 1540, 1387, 1307, 1240.

EXAMPLE 53 Synthesis of Compound 53

Compound 53 was obtained in 32.1 mg (yield: 78.5%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using 3,4-methylenedioxycinnamoyl chloride instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 53 are as follows.

¹ H--NMR (DMSO-d₆) δ(ppm); 8.68 (s 1H), 7.62 (d 1H J=15.3Hz), 7.50 (d 1H J=11.1Hz), 7.25 (dd 1H J=8.0, 1.1Hz), 7.12 (br s 1H), 6.97 (d 1H J=8.0Hz), 6.93 (d 1H J=15.3Hz), 6.09 (s 2H), 4.39 (d 1H J=10.8Hz), 4.26 (dd 1H J=10.8, 5.2Hz), 3.60 (s 3H), 2.99 (m 1H), 1.92 (dd 1H J=7.5, 3.4Hz), 1.45 (s 3H), 1.29 (t 1H J=41.1Hz).

EI--MS m/z; 448 (M⁺), 404, 227, 175, 148.

EXAMPLE 54 Synthesis of Compound 54

Compound 54 was obtained in 62.0 mg (yield: 72.8%) from 40 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 6-benzyloxy-5,7-dimethoxyindole-2-carboxylate instead of p-nitrophenyl 5-tertbutoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 54 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 9.24 (br s 1H), 7.49-7.52 (m 2H), 7.33-7.40 (m 3H), 7.17 (s 1H), 6.94 (d 1H J=2.4Hz), 6.79 (s 1H), 6.03 (br s 1H), 5.08 (s 2H), 4.45 (dd 1H J=10.1, 4.8Hz), 4.41 (d 1H J=10.0Hz), 4.04 (s 3H), 3.88 (s 3H), 3.75 (s 3H), 3.06 (m 1H), 2.25 (dd 1H J=7.6, 4.0Hz), 1.67 (s 3H), 1.29 (dd 1H J=4.6, 4.1Hz).

EI--MS m/z; 583 (M⁺), 549, 492, 311, 272, 220.

EXAMPLE 55 Synthesis of Compound 55

Compound 55 was obtained in 43.6 mg (yield: 78.1%) from 49 mg of Compound 54 in a manner similar to Example 8 except for using Compound 54 instead of Compound 6.

Physicochemical properties of Compound 55 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 9.53 (br s 1H), 9.48 (br s 1H), 8.51 (s 1H), 7.52-7.55 (m 2H), 7.31-7.42 (m 3H), 7.02 (d 1H J=2.4Hz), 6.89 (s 1H), 5.38 (s 1H), 5.11 (s 2H), 4.64 (dd 1H J=10.8, 9.3Hz), 4.55 (dd 1H J=10.9, 4.4 Hz), 4.19 (m 1H), 4.11 (s 3H), 4.05 (dd 1H J=10.0, 3.3Hz), 3.91 (s 3H), 3.75 (s 3H), 3.61 (dd 1H J=10.0, 8.8Hz), 1.71 (s 3H).

EI--MS m/z; 663, 665 (M⁺), 633, 635, 583 (M--HBr)⁺, 492 280.

IR (KBr) ν_(max) (cm⁻¹); 3330, 1740, 1699, 1610, 1584, 1498, 1420, 1307.

EXAMPLE 56 Synthesis of Compound 56

Compound 56 was obtained in 22.3 mg (yield: 56%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl p-methoxyphenoxyacetate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 56 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 7.14 (br 1H), 6.87 (d 2H J=8.9Hz), 6.84 (d 2H J=8.9 Hz), 5.99 (br s 1H), 4.70 (s 2H), 4.21 (d 1H J=10.8Hz), 4.12 (dd 1H J=10.8, 5.0Hz), 3.77 (s 3H), 3.74 (s 3H), 2.97 (dt 1H J=7.6, 4.9Hz), 2.17 (dd 1H J=7.6, 3.9Hz), 1.65 (s 3H), 1.08 (dd 1H J=4.6, 4.2Hz).

EI--MS m/z; 438 (M⁺), 379 (M--CO₂ CH₃)⁺, 315, 287, 255, 215.

EXAMPLE 57 Synthesis of Compound 57

Compound 57 was obtained in 20.5 mg (yield: 43.3%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 4-tert-butoxycarbonylaminocinnamate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 57 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 7.78 (d 1H J=15.4Hz), 7.50 (d 2H J=8.7Hz), 7.42 (d 2H J=8.7Hz), 6.90 (br 1H), 6.67 (s 1H), 6.67 (d 1H J=15.4Hz), 6.04 (s 1H), 4.23 (d 1H J=11.0Hz), 4.18 (dd 1H J=11.1, 4.9Hz), 3.75 (s 3H), 2.98 (m 1H), 2.25 (dd 1H J=7.6, 3.9Hz), 1.66 (s 3H), 1.53 (s 9H), 1.22 (t 1H J=4.5Hz).

EI--MS m/z; 519 (M⁺), 447, 419, 290, 234, 190, 146.

IR (KBr) ν_(max) (cm⁻¹); 1733, 1669, 1589, 1519, 1413, 1390, 1319, 1228, 1158.

EXAMPLE 58 Synthesis of Compound 58

Compound 58 was obtained in 26.5 mg (yield: 60.9%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 4-methoxycarbonylaminocinnamate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 58 are as follows.

EI--MS m/z; 477 (M⁺), 445, 386, 272, 204, 172.

IR (KBr) v _(max) (cm⁻¹); 1736, 1668, 1593, 1522, 1413, 1389, 1320, 1225.

EXAMPLE 59 Synthesis of Compound 59

Compound 59 was obtained in 36.4 mg (yield: 81.4%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 5-(3,4-dimethoxyphenyl)-2,4-pentadienoate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 59 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 7.96 (dd 1H J=15.5, 11.3Hz), 7.06-7.10 (m 2H), 6.79-6.91 (m 4H), 5.99 (br s 1H), 5.94 (d 1H J=11.3Hz), 4.15 (d 1H J=11.3Hz), 4.11 (dd 1H J=11.0, 4.6Hz), 3.93 (s 3H), 3.91 (s 3H), 3.75 (s 3H), 2.96 (m 1H), 2.23 (dd 1H J=7.6, 3.8Hz), 1.65 (s 3H), 1.20 (t 1H J=4.4Hz).

EI--MS m/z; 490 (M⁺), 431 (M--CO₂ CH₃)⁺, 217, 185.

IR (KBr) ν_(max) (cm⁻¹); 1735, 1669, 1577, 1507, 1380, 1267.

EXAMPLE 60 Synthesis of Compound 60

Compound 60 was obtained in 31.2 mg (yield: 79.5%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 5-phenyl-2,4-pentadienoate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 60 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 8.05 (ddd 1H J=15.6, 11.4, 0.9Hz), 7.52-7.55 (m 2H), 7.31-7.38 (m 3H), 6.90 (d 1H J=15.7Hz), 6.84 (t 1H J=11.4Hz) (1H overlapped), 6.04 (br s 1H), 5.99 (d 1H J=11.2Hz), 4.16 (d 1H J=10.7Hz), 4.11 (dd 1H J=11.2, 4.8Hz), 3.74 (s 3H), 2.96 (m 1H), 2.24 (dd 1H J=7.6, 3.8Hz), 1.66 (s 3H), 1.20 (dd 1H J=4.8, 41.1Hz).

EI--MS m/z; 430 (M⁺), 371 (M--CO₂ CH₃)⁺, 157.

EXAMPLE 61 Synthesis of Compound 61

Compound 61 was obtained in 28.5 mg (yield: 65%) from 25 mg of Compound 18 in a manner similar to Example 32 except for using p-nitrophenyl 4-methoxy-5-nitrocinnamate instead of p-nitrophenyl 5-tert-butoxycarbonylaminoindole-2-carboxylate.

Physicochemical properties of Compound 61 are as follows.

¹ H--NMR (CDCl₃) δ(ppm); 8.06 (d 1H J=2.3Hz), 7.77 (d 1H J=15.4Hz), 7.71 (dd 1H J=8.8, 2.3Hz), 7.14 (d 1H J=8.8Hz), 6.88 (br 1H), 6.72 (d 1H J=15.4 Hz), 6.00 (br s 1H), 4.24 (d 1H J=10.8Hz), 4.19 (dd 1H J=10.9, 4.8Hz), 4.02 (s 3H), 3.75 (s 3H), 3.01 (dt 1H J=7.5, 4.7Hz), 2.28 (dd 1H J=7.6, 3.9Hz), 1.66 (s 3H), 1.23 (dd 1H J=4.9, 4.0Hz).

REFERENCE EXAMPLE 1 Synthesis of Compound a

Compound a having the following structural formula was obtained in 69.5 mg (yield: 61.2%) from 50 mg (0.182 mmol) of Compound 18 in a manner similar to Example 10 except for using 81 mg (0.20 mmol) of p-nitrophenyl N-benzyloxycarbonyl-N-phenylglycinate instead of phenyl isocyanate. ##STR81##

Physicochemical properties of Compound a are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 9.34 (br 1H), 8.30 (s 1H), 7.43-7.45 (m 2H), 7.36 (m 2H), 7.22-7.28 (m 6H), 5.26 (br H), 4.99 (br s 1H), 4.60 (d 1H J=17.0Hz), 4.53 (d 1H J=17.0Hz), 4.17 (br 1H), 3.9-4.1 (br 3H), 3.70 (s H), 3.46 (br 1H), 1.49 (s 3H)

EI--MS m/z; 621, 623 (M⁺), 541 (M--HBr)⁺, 353, 355, 305

REFERENCE EXAMPLE 2 Synthesis of Compound b

Compound b having the following structural formula was obtained in 92.1 mg (yield: 79.6%) from 50 mg (0.18 mmol) of Compound 18 in a manner similar to Example 10 except for usig 80 mg (0.19 mmol) of p-nitrophenyl N-benzyloxycarbonylindoline-2-carboxylate instead of phenyl isocyanate. ##STR82## p Physicochemical properties of Compound b are as follows.

¹ H--NMR(CDCl₃) δ(ppm); 9.45 (br 1H), 8.22 (s 1H), 8.06 (d 1H J=8.0Hz) 7.32 (m 2H), 7.17 (d 1H J=7.5Hz), 6.99 7.08 (m 4H), 6.93 (m 2H), 5.12 (d 1H J=11.6Hz), 5.12 (m 1H), 5.01 (d 1H J=11.6Hz), 4.14 (br 1H), 3.82-3.92 (m 2H), 3.80 (s 3H), 3.58-3.65 (m 2H), 3.50 (m 1H), 3.24 (dd 1H J=16.3, 5.6Hz), 1.65 (s 3H)

EI--MS m/z; 633, 635 (M⁺), 553 (M--HBr)⁺, 494, 418, 364, 305, 273, 215

Pharmaceutical Preparation 1 (injection)

Compound 46 (10 mg) was dissolved in 50 ml of ethanol, and after stirring, ethanol was removed under reduced pressure. The residue thus obtained was dissolved in 1 l of sterile physiological saline solution. The solution was filtered through a membrane filter with pore size of 0.22μ (Millipore Inc, FGLD 14200) under a nitrogen gas pressure of 0.5 kg/cm². The filtrate was poured in 20 ml ampules (10 ml in each), and each ampule was sealed in a conventional manner to prepare injections.

Pharmaceutical preparation 2 (Tablet)

Tablets were prepared from 10 mg of Compound 46, 200 mg of lactose, 40 mg of corn starch, 4 mg of polyvinyl alcohol, 28 mg of Avicel and 1 mg of magnesium stearate. 

What is claimed is: PG,68
 1. A DC-88A derivative represented by general formula: ##STR83## wherein ##STR84## represents ##STR85## wherein R represents: ##STR86## wherein each of X₁, X₂, and X₃ independently represents hydrogen, --OH, --CHO, --OR₁, (wherein R₁ represents a straight or branched alkyl having 1 to 7 carbon atoms or benzyl), --OCOR₁ as described, --NO₂, --NH₂, --NR₂ R₃ (wherein each of R₂ and R₃ represents hydrogen or R₁, --NR₂ COR₁, --NHCO₂ R₁, --NHCONH₂, --SH, --SR₁, --SCOR₁, chlorine or bromine; or X₁ and X₂ are combined together to represent --OCH₂ O--; Z represents O, S or NH; Y represents --(CH₂)_(l) -- (wherein l is an integer of 0 to 7), --(CH═CH)_(m) -- (wherein m is an integer of 1 or 2), --Y'-- (wherein Y' represents O, S or NH), --Y'--(CH₂)_(n) -- (wherein n represents an integer of 1 to 4), --(CH₂)_(n) --Y'-- (wherein Y' and n have the same significances as described above), or ##STR87## (wherein p represents an integer of 0 to 4).
 2. A compound according to claim 1, wherein each of X₁, X₂ and X₃ independently represents hydrogen or --OCH₃ ; or X₁ and X₂ are combined together to represent --OCH₂ O--; Y is selected from the group consisting of single bond, --CH═CH--, --NH--, --NHCH₂ --, --CH₂ O-- and --OCH₂ --; Z represents O.
 3. A compound according to claim 2, wherein X₁ and X ₂ represents methoxy; X₃ represents hydrogen; Y represents --CH═CH--; and Z represents O. 